Medicament Delivery Device

ABSTRACT

A medicament delivery device includes a body having a proximal end and a distal end, in turn comprising a distal housing part, and a medicament container holder, adapted to receive a medicament container; a dose setting drum for setting a dose when rotated in a first direction and for delivering a dose when rotated in a second direction, and a drive drum sleeve selectively operably connectable to a piston plunger for delivering a dose.

TECHNICAL FIELD

The present invention relates to a medicament delivery device and inparticular a device capable of delivering a dose of medicament set byuser before delivery.

BACKGROUND

There are numerous devices for delivering medicament on the market andalso patented where the medicament is arranged in a container, such as asyringe, cartridge and the like, and wherein the medicament is exposedto pressure when it is to be delivered. A very common design is agenerally tubular compartment having a stopper in one end of thecompartment and a delivery member attached to the opposite end of thecompartment, such as, e.g., a needle, a nozzle or the like membercapable of delivering medicament to a patient.

In order to deliver a quantity of medicament, the stopper is exposed topressure, i.e. pushed into the compartment by a plunger rod, which couldbe done manually by a finger, which is the case for simple handheldsyringes, or by pressure means such as springs, which is common inautomatic or semi-automatic injectors. In this context, the so calledpen-injectors are becoming quite common, where the injection isperformed by manually pushing at a distal end of the device. With thistype of injector there has also been a development regarding deliveringdifferent dose quantities with the same device, i.e. to be able to set acertain prescribed dose before delivery.

A number of such devices have been developed, such as the devicedisclosed in EP-A-1 601 395. Here the device is arranged with a dosesetting drum that can be rotated in relation to a housing and a drivesleeve that, upon manual operation by a user, drives a plunger rod todeliver a set dose of medicament. In order to provide the function ofsetting a dose with the dose setting drum and delivering a dose with thedrive sleeve, there has to be some sort of connection/disconnectionmechanism between them. Thereby a clutch or uni-directional connectionmechanism has been developed for providing the desired function. Thissolution entails a number of components that are to interact with eachother as well as a number of threaded engagement and connectionmechanisms that require careful design in order for the manually appliedforce by a user not to be too large, or the device otherwise will notfunction properly. There is also a question whether the solutionaccording to EP-A-1 601 395 can provide the possibility of resetting aset dose in a simple and efficient manner.

SUMMARY

An object of the present invention is to provide a medicament deliverydevice wherein the drawbacks of the state of the art devices areremedied.

In order to overcome one or several of the above-mentioned problems, amedicament delivery device according to independent claim 1 is provided.

Further aspects, improvements and variations are disclosed in thedependent claims, the figures and the description.

In the present application, when the term “distal” is used, this refersto the direction pointing away from the dose delivery site. When theterm “distal part/end” is used, this refers to the part/end of thedelivery device, or the parts/ends of the members thereof, which underuse of the medicament delivery device is/are located furthest away fromthe dose delivery site. Correspondingly, when the term “proximal” isused, this refers to the direction pointing to the dose delivery site.When the term “proximal part/end” is used, this refers to the part/endof the delivery device, or the parts/ends of the members thereof, whichunder use of the medicament delivery device is/are located closest tothe dose delivery site. Further, the term “longitudinal”, with orwithout “axis”, refers to a direction or an axis through the device orcomponents thereof in the direction of the longest extension of thedevice or the component. In a similar manner, the term “transversal”,with or without “axis”, refers to a direction or an axis through thedevice or components thereof in a direction generally perpendicular tothe longitudinal direction. Also, if nothing else is stated, in thefollowing description wherein the mechanical structure of the device andthe mechanical interconnection of its components is described, thedevice is in an initial non-activated or non-operated state.

The invention provides a medicament delivery device having a housingwith a proximal end and a distal end. A hollow piston plunger isarranged within the housing. The piston plunger has a longitudinal axisgenerally corresponding with the longitudinal direction of themedicament delivery device.

Furthermore, a telescopic dose drum is concentrically arranged betweenthe housing and the piston plunger. The telescopic dose drum isbidirectional movable in relation to the housing and in relation to thepiston plunger when setting a dose and delivering a dose.

The medicament delivery device also comprises a piston plunger drivingmeans for driving the hollow piston plunger towards the proximal end.The piston plunger driving means comprises a hollow drive drum sleevethat is movable arranged within the hollow piston plunger and is fixedlyconnected to the telescopic dose drum. The hollow drive drum sleeve andthe hollow piston plunger are releasably coupleable to each other. Thepiston plunger driving means further comprises a resilient spinningelement having a longitudinally rod being movable arranged within thehollow drive drum sleeve. The longitudinally rod and the hollow drivedrum sleeve are releasably coupleable to each other; such that after adose is set, axial movement of the resilient spinning element towardsthe proximal end forces the longitudinally rod and the hollow drive drumsleeve to couple together and thereby the hollow drive drum sleeve andthe hollow piston plunger also to couple together whereby the hollowpiston plunger and the telescopic dose drum are displaced towards theproximal end for delivering the set dose, and such that after a set doseis delivered, axial movement of the resilient spinning element towardsthe distal end forces the longitudinally rod and the hollow drive drumsleeve to decouple and thereby the hollow drive drum sleeve and thehollow piston plunger also to decouple for setting a new dose.

The resilient spinning element may be configured to be axially spacedfrom a distal part of the hollow drive drum sleeve during setting a doseby a user, and to abut against the distal part of the hollow drive drumsleeve during delivery of a set dose.

The telescopic dose drum preferably comprises a first part (distal part)and a second part (proximal part) that are slidably arranged relative toeach other.

The medicament delivery device may further comprise at its distal end adose setting knob. The dose setting knob may be configured to be graspedby a user for setting a dose when being rotated in a first direction.

According to one embodiment of the medicament delivery device, the dosesetting knob is a separate component connected, preferably fixedlyconnected, with the first part of the dose drum at its distal end.According to another embodiment, the dose setting knob is integral withthe first part of the telescopic dose drum. The first part of thetelescopic dose drum may be configured to rotationally move distally inthe first direction relative to the housing during dose setting by thedose setting knob.

According to an alternative embodiment, the dose setting knob is aseparate component connected, preferably fixedly connected, with thedrive drum sleeve at its distal end. Alternatively, the dose settingknob is integral with the drive drum sleeve. The drive drum sleeve maybe is configured to rotationally move distally in the first directionrelative to the housing during dose setting by the dose setting knob.

The medicament delivery device may further comprise a medicamentcontainer holder adapted to receive a medicament container.

It is preferred that part of the outer circumferential surface of thepiston plunger is threaded. For example, a proximal part of the pistonplunger may comprise a threaded structure However, the invention alsoencompasses that the entire surface of the piston plunger is threaded.On its outer surface, the piston plunger may comprise at least onelongitudinal groove, e.g., two grooves. Furthermore, the proximal end ofthe piston plunger may be arranged with a washer and a stopper. Thestopper at the proximal end of the piston plunger may be intended to bemovable received inside the medicament container.

The medicament delivery device may further comprise an unidirectionalmeans for preventing movement of the piston plunger in the distaldirection during setting a dose.

According to a first preferred embodiment, the unidirectional meanscomprises an insert having a central longitudinal passage having a firstdiameter. The passage is provided with threads mating with the threadsof the outer circumferential surface of the piston plunger, wherein theinsert, in the initial position of the medicament delivery device, islocated at the proximal end of the piston plunger. The insert mayfurther comprise at its distal side a central bore coaxial with thecentral longitudinal passage. The central bore may have a seconddiameter being larger than the first diameter. Furthermore, the innersurface of the bore may be provided with a circumferentially extendingratchet. The insert may be a separate component being fixedly connectedto the housing or may be a component integral with the housing.

The unidirectional means of this embodiment may further comprise a backrotation blocking element that comprises at its circumferential surfaceat least one arm extending in circumferential direction and beingflexible in radial direction. The one or more arms may comprise a ledgehaving a shape complementary to the ratchet of the insert. The at leastone arm with its ledge may be resilient such that rotation of the backrotation blocking element against the ratchet during medicament deliverygenerates an audible feedback.

The back rotation blocking element may comprise a longitudinal centralpassage having at least one radially inwardly directed protrusion. Theat least one protrusion may be each received in a correspondinglongitudinal groove on the outer surface of the piston plunger. Thisstructure provides a rotational lock of the piston plunger but allows amovement of the piston plunger in the longitudinal direction.

According to another embodiment, the unidirectional means comprises aninsert having a central longitudinal passage having a first diameter,central longitudinal passage having at least one radially inwardlydirected protrusion, the at least one protrusion being each received ina corresponding longitudinal groove on the outer surface of the pistonplunger. This structure provides a rotational lock of the piston plungerbut allows a movement of the piston plunger in the longitudinaldirection. The insert may further comprise at its distal side a centralbore coaxial with the central longitudinal passage. The central bore mayhave a second diameter being larger than the first diameter, the innersurface of the bore being provided with a circumferentially extendingratchet.

In this embodiment, the unidirectional means further comprises a backrotation blocking element having a central longitudinal passage having afirst diameter, the passage being provided with threads mating with thethreads of the outer circumferential surface of the piston plunger. Theback rotation blocking element, in the initial position of themedicament delivery device, may be located at the proximal end of thepiston plunger. The back rotation blocking element may comprise at itscircumferential surface at least one arm extending in circumferentialdirection and being flexible in radial direction, the at least one armcomprising a ledge having a shape complementary to the ratchet of theinsert.

The ratchet may comprise steep front edges and ramp shaped trailingedges such that the interaction of the ratchet with the at least one armis to have a unidirectional coupling for the piston plunger.

According to a still further embodiment, the unidirectional meanscomprises a self-locking thread connection between the threaded matingbetween the insert and the piston plunger.

The inner circumferential surface of the piston plunger may comprise aplurality of longitudinally extending splines and the drive drum sleevecomprises at least one flexible arm being configured to releasablyengage with the plurality of longitudinally extending splines of thepiston plunger. It is preferred that the longitudinal rod of theresilient spinning element is operably connected with the hollow drivedrum sleeve such that the axial movement of the resilient spinningbutton in proximal direction forces the at least one flexible arm toengage with the plurality of longitudinally extending splines of thepiston plunger.

In the medicament delivery device of a preferred embodiment, theresilient spinning element is configured to stay rotationallyimmobilized during axial movement thereof.

The outer circumferential surface of the first part of the telescopicdose drum may be threadedly connected to a mating structure on the innercircumferential surface of the housing. The inner circumferentialsurface of the second part of the telescopic dose drum may be threadedlyconnected to the threaded outer circumferential surface of the pistonplunger. The threaded connection between the first part of thetelescopic dose drum and the inner circumferential surface of thehousing has a pitch different to the pitch of the threaded connection ofthe inner circumferential surface of the second par of the telescopicdose drum and the threaded outer circumferential surface of the pistonplunger.

In more detail, the distal part may comprise a helically or spirallyextending groove on its outer side surface. The groove may extend allthe way from the proximal end to the distal end of the distal part ofthe dose drum. The groove is intended to cooperate with at least oneprotrusion or spirally extending ledge segment arranged on the innersurface of the housing such that the dose drum is rotationally connectedto the housing, whereby mutual rotation causes movement in thelongitudinal direction of the parts. The distal end area of the firstpart of the dose drum is further arranged with a locking structure thatengages with the locking structure of the drive drum sleeve when thedrive drum sleeve is moved into the piston plunger during assembly ofthe medicament delivery device.

The inner circumferential surface of the second part of the telescopicdose drum may be threadedly connected to the threaded outercircumferential surface of the piston plunger. In particular, theproximal end of the second part may comprise a threaded structure. Thethreaded connection between the first part of the telescopic dose drumand the inner circumferential surface of the housing has a pitchdifferent to the pitch of the threaded connection of the innercircumferential surface of the second part of the telescopic dose drumand the threaded outer circumferential surface of the piston plunger.

The piston plunger may comprises on its outer surface a stop feature forinhibiting rotation of the telescopic dose drum and the drive drumsleeve when the set dose equals the remaining dose in the medicamentcontainer.

The drive drum sleeve may be of generally tubular shape and is arrangedradially inside the piston plunger. The drive drum sleeve may beprovided with a distal end wall transversal to the longitudinal axis ofthe drive drum sleeve. The distal end wall has central opening and thedrive drum sleeve is hollow in order to receive the resilient spinningelement therein. The proximal end of the drive drum sleeve may compriseone or more, for example two, flexible arms extending in the proximaldirection. The arms are flexible in that their proximal ends areradially deflectable upon application of a radial force thereon. Theouter surface of each flexible arm may comprise a radially projectingpiston plunger engagement protrusion for selectively engaging with thelongitudinal splines or ribs on the inner surface of the piston plunger.The shape of the protrusions may generally correspond to the shape ofthe circumferentially arranged ribs on the piston plunger. The innersurface of each flexible arm may comprise a radially engagementprotrusion for selective engagement with the resilient spinning elementlocated within the hollow drive drum sleeve.

The distal end wall may forms a coupling element by means of twoproximally extending locking arms. The locking arms comprise at theirrespective pouter surface a locking structure for locking the drive drumsleeve to the inner surface of a dose drum.

The resilient spinning element may comprise a longitudinal rod and adistal push button. The push button intended to act as a contact surfacefor a finger of a user during drug delivery. As described above, thelongitudinal rod of the resilient spinning element is accommodatedwithin the hollow drive drum sleeve. At its proximal end, thelongitudinal rod may comprise an engagement structure comprising a firstcircumferential ring-like protrusion having a diameter larger than thediameter of the longitudinal rod and a second circumferential ring-likeprotrusion having a diameter larger than the diameter of thelongitudinal rod. The second protrusion is preferably located at theproximal end of the longitudinal rod, and the first protrusion islocated distal from the second protrusion. The first protrusion and thesecond protrusion are axially spaced from each other such that acircumferential groove is formed there between. The size of the grooveand the location on the longitudinal groove may be such that theradially inwardly directed protrusion on the flexible arms of the drivedrum sleeve is initially received in the groove. In such initial stage,the flexible arms are not deflected radially outwards but are in atension-free state.

The axial length of the resilient spinning element in comparison to thedrive drum sleeve is preferably such that in the initial state of themedicament delivery device, i.e. with the engagement protrusion beingreceived in the groove, the proximal surface of the push button isspaced from the distal surface of the coupling element by a gap). Thisgap is maintained when a dose is set by a user and the first part of thedose drum, the drive drum sleeve and the resilient spinning element aremoved distally. However, as soon as the push button is pushed pinproximal direction, the push button first bridges the gap thereby movingthe longitudinal rod in proximal direction relative to the drive drumsleeve. Due to such relative displacement, the distally located firstring-shaped protrusion is pressed against the engagement protrusion onthe flexible arms, thus deflecting the arms outwardly and intoengagement with the longitudinal splines on the inner surface of thepiston plunger.

The medicament delivery device may be an injection device, preferably apen injector.

Other aspects, features, and advantages will be apparent from thesummary above, as well as from the description that follows, includingthe figures and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures below disclose an embodiment of the invention forillustrational purposes only. In particular, the disclosure within thefigures is not meant to limit the range of protection of the invention.The embodiment shown may be modified in many ways within the scope ofthe claims.

FIG. 1 shows a perspective view of a medicament delivery deviceaccording to a preferred embodiment of the invention, shown in theinitial state;

FIG. 2 shows a perspective view of a medicament delivery deviceaccording to the preferred embodiment of FIG. 1, shown in the state whena dose is set;

FIG. 3 shows a perspective view of a medicament delivery deviceaccording to the preferred embodiment of FIG. 1, shown after a set dosehas been delivered;

FIG. 4 shows a perspective view of a medicament delivery deviceaccording to the preferred embodiment of FIG. 1, shown in a state havingall medicament delivered;

FIG. 5 shows an exploded view of the medicament delivery deviceaccording to the preferred embodiment of FIG. 1;

FIG. 6 shows a partly exploded view of the medicament delivery deviceaccording to FIG. 1;

FIG. 7 shows another partly exploded view of the medicament deliverydevice according to FIG. 1;

FIG. 8 shows a cross-sectional view of the medicament delivery deviceaccording to FIG. 1, shown in the initial state;

FIG. 9 shows a cross-sectional view of the medicament delivery deviceaccording to FIG. 2, i.e., in the state when a dose is set;

FIG. 10 shows a cross-sectional view of the medicament delivery deviceat the beginning of the process of dose delivery;

FIG. 11 shows a cross-sectional view of the medicament delivery deviceaccording to FIG. 3, i.e., after a set dose has been delivered;

FIG. 12 shows a cross-sectional view of the medicament delivery deviceat the beginning of the process of setting a new dose;

FIG. 13 shows a cross-sectional view of the medicament delivery deviceaccording to FIG. 4, i.e., in a state having all medicament delivered.

DETAILED DESCRIPTION Mechanical Structure of an Embodiment

FIG. 1 shows a perspective view of a medicament delivery deviceaccording to a preferred embodiment of the invention. The medicamentdelivery device has a proximal end and a distal end and comprises ahousing 10 having a proximal part or end 11 and a distal part or end 12.In the assembled state of the medicament delivery device, the housing 10forms part of the outer surface or appearance of the medicament deliverydevice. It is however to be understood that the housing may be designedin many other ways.

The medicament delivery device further comprises a medicament containerholder 80 which accommodates a medicament container. The medicamentcontainer holder 80 also forms part of the outer surface or appearanceof the medicament delivery device. The proximal part of the containerholder 80 is further arranged with a neck 82 at its proximal end forattaching a per se known and conventional injection needle (not shown).It is however to be understood that other types of connection members,such as bayonet fitting luer-lock fittings and the like may be arranged.Also, the medicament container may have an injection needle integratedin its body whereby the neck portion 82 may be omitted.

A cap (not shown) may be provided for releasably covering the proximalend of the device, and thereby the proximal end of the medicamentcontainer holder 80, when not in use.

The medicament container holder 80 of the medicament delivery devicecomprises a window 81 that allows the user to view the progress ofmedicament delivery, i.e. whether the medicament delivery device isstill in its initial stage with the medicament not yet being injected,or whether the medicament container is already emptied. Through window81, the user can see the medicament container accommodated at least inthe medicament container holder 80 (the distal part of the medicamentcontainer may reach into the proximal part of the housing 10). In apreferred embodiment, two such windows are provided located at oppositesides of the medicament container holder 80.

Furthermore, at the proximal end 12 of the housing 10, a further window13 is provided that is used to indicate a set dose to a user, asdescribed in more detail below. At the proximal end 12 of housing 10, adose setting knob 41 a for dose setting projects distally.

FIG. 1 shows the medicament delivery device in the initial state. Whenthe user grasps the dose setting knob 41 a and rotates it in a firstdirection, for example in clockwise direction, the dose setting knob 41a and other components move distally, as will be explained in detailbelow, in order to set a dose. FIG. 2 shows a perspective view of themedicament delivery device in such state, i.e. when a dose is set.

FIG. 3 shows a perspective view of the medicament delivery device aftera set dose has been delivered. As can be seen, the dose setting knob 41a and the components linked therewith were moved proximally and the dosesetting knob 41 a is again in its initial position. However, as can beseen at window 81, the piston plunger 20 of the medicament deliverydevice has been displaced in proximal direction and a stopper 29 withinthe medicament container can now be seen through the window(s) 81.

FIG. 4 then shows a perspective view of the medicament delivery devicein a state having all medicament, i.e. several individual dosesdelivered. The stopper 29 is now located at the proximal end of themedicament container 85, and part of the piston plunger 20 with itsthreaded surface 21 can be seen through windows 81.

The medicament container holder 80 is arranged with attachment means forconnecting or attaching it to the proximal housing part 11. In theembodiment shown the attachment means comprise a protrusion 83 (see FIG.5) fitting into a corresponding recess 14. It is however to beunderstood that other attachment members may be utilized, such asbayonet fittings, threads, or the like for attaching the medicamentcontainer holder 80 with the housing 10.

An elongated piston plunger 20 (see FIGS. 5 to 7) is arranged inside thehousing 10 and has a longitudinal axis generally corresponding with thelongitudinal direction of the medicament delivery device. The pistonplunger 20 is arranged with threads 21 on at least part of its outersurface. In the preferred embodiment shown in the drawings, a proximalpart of the piston plunger 20 comprises a threaded structure 21. On itsouter surface, the piston plunger 20 comprises at least one longitudinalgroove 25 (in the shown embodiment, two such grooves 25 are provided).The proximal end of the piston plunger 20 is arranged with a washer orspinner 28 adapted to abut the stopper 29. The stopper 29 is intended tobe movable received inside the medicament container 85.

The piston plunger 20 fits into an insert 50 arranged with a centralpassage 51, the centre of which generally coincides with thelongitudinal axis of the medicament delivery device. The central passage51 of the thread insert is arranged with threads 52 of complementarydesign as the threads 21 of the piston plunger 20. The outer surface ofthe insert 50 comprises at least one protrusion 53 or the like, fittinginto corresponding recesses 15 on the inner surface of the housing 10,whereby the insert 50 is locked to the proximal housing part 10. Asshown in FIG. 5, recess 15 in the housing may be formed as a throughhole.

The insert 50 further comprises a central bore 54 at the distal side ofthe thread insert 50. The diameter of the central bore 54 is larger thanthe diameter of the central passage 51 so that a stepped configurationis provided. The inner circumferential surface of the central bore 54 isarranged with a circumferentially extending ratchet 55 arranged withsaw-tooth shaped teeth.

The ratchet 55 cooperates with a ring-shaped back rotating blockingelement 60 which is arranged with two oppositely positioned arms 62,extending on the outer circumferential surface 61 generally in thecircumferential direction of the blocking element 60. Although two sucharms 62 are shown in FIGS. 5 and 7, a single arm may as well suffice, ormore than two arms may be provided, depending on the size of theblocking member 60. The one or more arms 62 are flexible in thegenerally radial direction. On the outwardly directed surfaces of thearm(s) 62, a ledge 63 is arranged. Each ledge 63 has a shapecomplementary to the ratchet 55 of the thread insert 50. The backrotating blocking element 60 is further arranged with a central passage65 through which the piston plunger 20 extends. The central passage 65is arranged with radially inwardly directed protrusions or ribs 66,which protrusions 66 fit into the elongated grooves 25 on the outersurface of the piston plunger 20. This structure provides a rotationallock of the piston plunger 20 but allows a movement of the pistonplunger 20 in the longitudinal direction.

The piston plunger 20 is further arranged with a plurality oflongitudinal splines or ribs 23 provided on the inner circumferentialsurface 22 of the hollow piston plunger 20. A drive drum sleeve 30 ofgenerally tubular shape is arranged radially inside the piston plunger20. The drive drum sleeve 30 is provided with a distal end wall 31transversal to the longitudinal axis of the drive drum sleeve 30. Thedistal end wall 31 has central opening and the drive drum sleeve ishollow in order to receive a resilient spinning element 70 therein, aswill be described below. The proximal end of the drive drum sleeve 30comprises one or more, preferably two, flexible arms 33 extending in theproximal direction. The arms 33 are flexible in that their proximal endsare radially deflectable upon application of a radial force thereon, aswill be describe below. The outer surface of each flexible arm 33comprises a radially projecting piston plunger engagement protrusion 34for selectively engaging with the longitudinal splines 23 on the innersurface 22 of the piston plunger 25. The shape of the protrusions 34generally corresponds to the shape of the circumferentially arrangedribs 23 on the piston plunger 20. The inner surface of each flexible arm33 comprises a radially engagement protrusion 37 for selectiveengagement with the resilient spinning element 70 located within thehollow drive drum sleeve 30.

The distal end wall 31 forms a coupling element by means of twoproximally extending locking arms 35. The locking arms 35 comprise attheir respective pouter surface a locking structure 36 for locking thedrive drum sleeve 30 to the inner surface of a dose drum 40.

Outside the piston plunger 20 as seen in a radial direction, atelescopic dose (setting) drum 40 is arranged. The dose drum 40 has agenerally tubular shape and is positioned coaxial with the pistonplunger 20 as well as the housing 10. The dose drum 40 comprises afirst, distal, part 41 and a second, proximal, part 42 being slidablyarranged relative to each other. The distal part 41 is located coaxiallyradially outside of the proximal part 42 of the dose drum 40.

The distal part 41 comprises a helically or spirally extending groove 49on its outer side surface 41. The groove 49 extends all the way from theproximal end to the distal end of the distal part 41 of the dose drum40. The groove 49 is intended to cooperate with at least one protrusionor spirally extending ledge segment 16 (FIG. 5) arranged on the innersurface of the housing 10 such that the dose drum 40 is rotationallyconnected to the housing 10, whereby mutual rotation causes movement inthe longitudinal direction of the parts. The distal end area of thefirst part 41 of the dose drum 40 is further arranged with a lockingstructure that engages with the locking structure 36 of the drive drumsleeve 30 when the drive drum sleeve 30 is moved into the piston plunger20 during assembly of the medicament delivery device.

At the distal end of the first part 41 the dose setting knob 41 a isarranged. The dose setting knob 41 a comprises a proximally directedgenerally tubular part having a diameter somewhat larger than the outersurface of the first part 41 of the dose drum 40. The outermost diameterof the dose setting knob 41 a is preferably flush with the outerdiameter of housing 10. The first part 41 of the telescopic dose drum 40is thus configured to rotationally move distally in the first directionrelative to the housing 10 during dose setting by the dose setting knob41 a.

The inner circumferential surface 44 of the second part 42 of thetelescopic dose drum 40 is threadedly connected to the threaded outercircumferential surface 21 of the piston plunger 20. In particular, theproximal end of the second part 42 comprises a threaded structure 45(FIG. 6). The threaded connection between the first part 41 of thetelescopic dose drum 40 and the inner circumferential surface of thehousing 10 has a pitch different to the pitch of the threaded connectionof the inner circumferential surface 44 of the second part 42 of thetelescopic dose drum 40 and the threaded outer circumferential surface21 of the piston plunger 20.

As can also be seen in FIG. 6, the piston plunger 20 comprises on itsouter surface a stop feature 26 for inhibiting rotation of thetelescopic dose drum 40 and the drive drum sleeve 30 when the set doseequals the remaining dose in the medicament container.

The resilient spinning element 70 comprises a longitudinal rod 71 and adistal push button 72. The push button intended to act as a contactsurface for a finger of a user during drug delivery, as will bedescribed. As described above, the longitudinal rod 71 of the resilientspinning element 70 is accommodated within the hollow drive drum sleeve30. At its proximal end, the longitudinal rod 71 comprises an engagementstructure comprising a first circumferential ring-like protrusion 73having a diameter larger than the diameter of the longitudinal rod and asecond circumferential ring-like protrusion 74 having a diameter largerthan the diameter of the longitudinal rod. The second protrusion 74 ispreferably located at the proximal end of the longitudinal rod, and thefirst protrusion 73 is located distal from the second protrusion 74. Thefirst protrusion 73 and the second protrusion 74 are axially spaced fromeach other such that a circumferential groove 75 is formed therebetween. The size of the groove 75 and the location on the longitudinalrod 71 is such that the radially inwardly directed protrusion 37 on theflexible arms 33 of the drive drum sleeve 30 is initially received inthe groove 75. In such initial stage, the flexible arms 33 are notdeflected radially outwards but are in a tension-free state.

The axial length of the resilient spinning element 70 in comparison tothe drive drum sleeve 30 is such that in the initial state of themedicament delivery device, i.e. with the engagement protrusion 37 beingreceived in the groove 75, the proximal surface of the push button 72 isspaced from the distal surface of the coupling element 31 by a gap 76(see, e.g., FIG. 8). This gap 76 is maintained when a dose is set by auser (see FIG. 9) and the first part 41 of the dose drum 40, the drivedrum sleeve 30 and the resilient spinning element 70 are moved distally.However, as soon as the push button 72 is pushed towards the proximaldirection, the push button 72 first bridges the gap 76 thereby movingthe longitudinal rod 71 in proximal direction relative to the drive drumsleeve 30. Due to such relative displacement, the distally located firstring-shaped protrusion 73 is pressed against the engagement protrusion37 on the flexible arms 33, thus deflecting the arms 33 outwardly andinto engagement with the longitudinal splines on the inner surface 22 ofthe piston plunger 20. Moreover, as soon as the push button 72 isreleased, the deflected arms 33 strive to move inwardly such that theengagement protrusion 37 are received in the groove 75 whereby thelongitudinal rod 71 is moved in the distal direction relative to thedrive drum sleeve 30. It is also possible that the device furthercomprises a resilient member arranged in the gap 76, wherein saidresilient member is a sole component or is integral with either thedrive drum sleeve 30 or the resilient spinning element 70.

Description of the Function and Operation of the Embodiment SettingOperation for a Dose to be Delivered

FIG. 8 shows a cross-sectional view of the medicament delivery device inthe initial state.

In order for a dose to be delivered, the device must be operated to seta dose. In order to set a dose to be delivered the user grips thehousing 10 and the distally arranged dose setting knob 41 a and turnsthem in relation to each other, where the dose setting knob 41 a isturned in the clockwise direction, for example. The turning of the dosesetting knob 41 a will cause the first part 41 of the dose drum 40 to berotated. The connection between the helical groove 49 of the dose drum40 and the spiral ledge segment of the housing 10, the rotation willcause the first part 41 of the dose drum 40 to move in the distaldirection in relation to the housing 10. Inside the dose setting drum 40the drive drum sleeve 30 will also rotate because of the rotational lockboth at the distal end 31 of the drive drum sleeve 30 with the dose drum40. Thus the drive drum sleeve 30 is rotationally connected to the dosedrum 40.

The longitudinal ribs 48 on the inner surface of the first part 41 ofthe dose drum 40 are in contact with the longitudinal grooves on theouter surface of the second part 42 of the dose drum 40. Thus, the firstpart can slide relative to the second part. Furthermore, the second part42 is also rotated and due to the threaded 45 engaging into the threadedsurface of the piston plunger 20, the second part 42 also movesdistally, albeit at a lower speed than the first part 41 due to thedifferent pitches. Rotation of the second part 42 also causes a certainturning force on the piston plunger 20, which also urges the backrotating blocking element 60 to turn due to the rotational lock betweenthe blocking element 60 and the piston plunger 20 because of theprotrusions 66 of the back rotating blocking element 60 fitting into thelongitudinal grooves 25 of the piston plunger 24. However, the arms 62of the back rotating blocking element 60 are directed such andcooperating such with the ratchet 55 of the thread insert 50 that anyrotation of the back rotating blocking element 60 is prevented. Thus thepiston plunger 20 is prevented from rotating. During rotation,preferably indicia (not shown) on the dose drum 40 are shown through thewindow or opening 13 at the distal end 12 of the housing 10. The patientthus rotates the dose setting knob 41 a until the prescribed dosequantity is displayed.

If the user by mistake has set a too large dose, he/she simply turns thedose setting knob 41 a in the opposite direction, whereby both the dosedrum 40 and the drive drum sleeve 30 are turned in the oppositedirection until the correct dose has been reached.

FIG. 9 shows a cross-sectional view of the medicament delivery device inthe state when a dose is set. In particular, it can be seen that the gap76 still exists.

Delivery Operation of a Pre-Set Dose of Medicament

In order to deliver a dose of medicament, the user presses the proximalend of the device against a dose delivery site, and in particular aninjection site when the medicament delivery member is an injectionneedle. The next step is to press on the push button 72 at the distalend of the device.

FIG. 10 shows a cross-sectional view of the medicament delivery deviceat the beginning of the process of dose delivery. As can be seen, thegap 76 is now closed due to the force applied by the user and the button72 contacts the distal coupling member 31 of the drive drum sleeve 30.

The force on the push button 72 will first bring the drive drum sleeve30 into engagement with the inner surface of the piston plunger 20, asalready described above. Secondly, once the gap 76 has been bridged, theforce on the push button 72 urges the dose activator knob 41 a in theproximal direction. This proximal force will be transferred to the dosedrum 40 and due to the threaded connection with the housing 10, the dosesetting drum 40 will rotate, now in the anti-clockwise direction, andmove in the proximal direction. Because of the rotational lock betweenthe dose drum 40 and the drive drum sleeve 30, the latter will alsorotate. Due to the radial flexing of the arms 33 of the drive drumsleeve 30, the inwardly directed protrusions 34 of the drive drum sleeve30 firmly engage the splines 23 of the piston plunger 20.

Thus when now the dose drum 40 and the drive drum sleeve 30 rotate, thelatter will urge the piston plunger 20 to rotate as well. This rotationin the anti-clockwise direction will be allowed by the back rotatingblocking element 60 due to the design of its arms 62 in contact with theratchet 55 of the thread insert 50. The piston plunger 20 will thusrotate together with the back rotating blocking element 60, and the arms62 of the back rotating blocking element 60 sliding over the ratchet 55of the thread insert 50 will provide audible and tactile information.Further the rotation of the piston plunger 20 will cause it to be movedin the proximal direction due to the threaded connection with the threadinsert 50, whereby the movement of the piston plunger 20 will urge thestopper 29 in the proximal direction, thereby expelling a dose ofmedicament through the dose delivery member. The dose has been deliveredwhen the dose drum 40 has moved back to its initial position, whichcould be limited by some sort of blocking member (not shown) preventingfurther movement or rotation of the dose drum.

FIG. 11 shows a cross-sectional view of the medicament delivery deviceafter a set dose has been delivered.

The device may now be removed from the dose delivery site, and themedicament delivery member discarded. If the medicament container 85still contains a large enough dose to be delivered, the above steps maybe repeated from the step “Setting operation for a dose to bedelivered”.

FIG. 12 shows a cross-sectional view of the medicament delivery deviceat the beginning of the process of setting a new dose.

FIG. 13 shows a cross-sectional view of the medicament delivery devicein a state having all medicament delivered. The stopper 29 is located atthe proximal wall of the medicament container.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, such illustration and descriptionare to be considered illustrative or exemplary and not restrictive. Itwill be understood that changes and modifications may be made by thoseof ordinary skill within the scope of the following claims. Inparticular, the present invention covers further embodiments with anycombination of features from different embodiments described above andbelow.

Furthermore, in the claims the word “comprising” does not exclude otherelements or steps, and the indefinite article “a” or “an” does notexclude a plurality. A single unit may fulfil the functions of severalfeatures recited in the claims. The terms “essentially”, “about”,“approximately” and the like in connection with an attribute or a valueparticularly also define exactly the attribute or exactly the value,respectively. Any reference signs in the claims should not be construedas limiting the scope.

1-30. (canceled)
 31. A medicament delivery device, comprising: a housinghaving a proximal end and a distal end; a hollow piston plunger beingarranged within the housing; and a telescopic dose drum beingconcentrically arranged between the housing and the piston plunger, thetelescopic dose drum being bidirectional movable in relation to thehousing and in relation to the piston plunger when setting a dose anddelivering a dose, wherein the telescopic dose drum comprises a first,distal part and a second, proximal part being slidably arranged relativeto each other.
 32. The medicament delivery device of claim 31, furthercomprising a dose setting knob at a distal end of the first part of thedose drum, the dose setting knob configured to be grasped by a user forsetting a dose when being rotated in a first direction.
 33. Themedicament delivery device of claim 32, wherein the dose setting knob isa separate component connected with the distal end of the first part ofthe dose drum, or wherein the dose setting knob is integral with thefirst part, whereby the first part of the telescopic dose drum isconfigured to rotationally move distally in the first direction relativeto the housing during dose setting by the dose setting knob.
 34. Themedicament delivery device of claim 31, further comprising a medicamentcontainer holder adapted to receive a medicament container.
 35. Themedicament delivery device of claim 31, further comprising aunidirectional means for preventing movement of the piston plunger inthe distal direction during setting a dose.
 36. The medicament deliverydevice of claim 35, wherein part of an outer circumferential surface ofthe piston plunger is threaded.
 37. The medicament delivery device ofclaim 36, wherein the unidirectional means comprises an insert having acentral longitudinal passage having a first diameter, the passage beingprovided with threads mating with the threads of the outercircumferential surface of the piston plunger, wherein the insert, inthe initial position of the medicament delivery device, is located atthe proximal end of the piston plunger.
 38. The medicament deliverydevice of claim 37, wherein a distal side of the insert furthercomprising a central bore coaxial with the central longitudinal passage,the central bore having a second diameter being larger than the firstdiameter, the inner surface of the bore being provided with acircumferentially extending ratchet.
 39. The medicament delivery deviceof claim 37, wherein the insert is a separate component being fixedlyconnected to the housing or wherein the insert is a component integralwith the housing.
 40. The medicament delivery device of claim 38,wherein the unidirectional means further comprises a back rotationblocking element, comprising at its circumferential surface at least onearm extending in circumferential direction and being flexible in radialdirection, the at least one arm comprising a ledge, the ledge having ashape complementary to the ratchet of the insert.
 41. The medicamentdelivery device of claim 40, wherein the at least one arm with its ledgeis resilient such that rotation of the back rotation blocking elementagainst the ratchet during medicament delivery generates an audiblefeedback.
 42. The medicament delivery device of claim 40, the backrotation blocking element comprising a longitudinal central passagehaving at least one radially inwardly directed protrusion, the at leastone protrusion being each received in a corresponding longitudinalgroove on the outer surface of the piston plunger.
 43. The medicamentdelivery device of claim 36, wherein the unidirectional means comprisesan insert having a central longitudinal passage having a first diameter,central longitudinal passage having at least one radially inwardlydirected protrusion, the at least one protrusion being each received ina corresponding longitudinal groove on the outer surface of the pistonplunger.
 44. The medicament delivery device of claim 43, a distal sideof the insert further comprising a central bore coaxial with the centrallongitudinal passage, the central bore having a second diameter beinglarger than the first diameter, the inner surface of the bore beingprovided with a circumferentially extending ratchet.
 45. The medicamentdelivery device of claim 44, wherein the unidirectional means furthercomprises a back rotation blocking element having a central longitudinalpassage having a first diameter, the passage being provided with threadsmating with the threads of the outer circumferential surface of thepiston plunger, wherein the back rotation blocking element, in theinitial position of the medicament delivery device, is located at theproximal end of the piston plunger.
 46. The medicament delivery deviceof claim 45, wherein the back rotation blocking element comprises at itscircumferential surface at least one arm extending in circumferentialdirection and being flexible in radial direction, the at least one armcomprising a ledge, the ledge having a shape complementary to theratchet of the insert.
 47. The medicament delivery device of claim 40,wherein the ratchet comprises steep front edges and ramp shaped trailingedges such that the interaction of the ratchet with the at least one armis to have a unidirectional coupling for the piston plunger.
 48. Themedicament delivery device of claim 37, wherein the unidirectional meanscomprises a self-locking thread connection between a threaded matingbetween the insert and the piston plunger.
 49. The medicament deliverydevice of claim 31, wherein an inner circumferential surface of thepiston plunger comprises a plurality of longitudinally extendingsplines.
 50. The medicament delivery device of claim 31, wherein anouter circumferential surface of the first part of the telescopic dosedrum is threadedly connected to a mating structure on an innercircumferential surface of the housing.
 51. The medicament deliverydevice of claim 31, wherein an inner circumferential surface of thesecond part of the telescopic dose drum is threadedly connected to athreaded outer circumferential surface of the piston plunger.
 52. Themedicament delivery device of claim 41, wherein the threaded connectionbetween the first part of the telescopic dose drum and an innercircumferential surface of the housing has a pitch different to thepitch of the threaded connection of the inner circumferential surface ofthe second part of the telescopic dose drum and the threaded outercircumferential surface of the piston plunger.
 53. The medicamentdelivery device of claim 31, wherein the device is an injection device,preferably a pen injector.